Abstract: Litter layer plays a vital role in the hydrological function of forest ecosystems. We conducted a litter soaking experiment in the laboratory to examine litter hydrological characteristics. Litter was collected from four typical forests in Xishuangbanna, including tropical seasonal rainforest, rubber (Hevea brasiliensis) monoculture, and two rubber agroforestry systems (rubberFlemingia macrophylla and rubberTheobroma cacao). The aim of this study was to provide scientific reference for water resources management under different land use types in tropical area. Our results showed that the total standing litter in the tropical seasonal rainforest was significantly higher than that in other forests (P<0.05), with no difference between rubber monoculture and rubber agroforestry systems (P>0.05). Leaf litter was the largest litter component (accounting for more than 60% of the total) in all forest types. Except for tropical seasonal rainforest, the maximum and minimum water storage rates of litter components in different forest types were leaf > mixed litter > branch+bark > reproductive part. The maximum and minimum water storage rates of each component in tropical seasonal rainforest were significantly higher than that of rubber monoculture (P<0.05). The time-dependent changes in water-holding capacity of litter components were consistent across all the forest types. The waterholding capacity increased rapidly at the beginning stage, then increased slowly, and reached saturation after soaking for about 20 h. At each measurement incidence, waterholding capacity of litters from tropical seasonal rainforest and rubber F. macrophylla agroforestry system was higher than that from rubber T. cacaoagroforestry system and rubber monoculture. The rubber monoculture had the lowest water interception through litter (4.69 t·hm^-2), of which 1.7 times in the tropical rainforest and 2.1 times in rubberF. macrophylla agroforestry system. These results indicated that the transformation of a tropical seasonal rainforest to rubber monoculture reduced litter hydrological function. The construction of an agroforestry system with a better litter water interception and holding capacity such as rubberF. macrophylla and rubber T. cacao would have ecological and environmental benefits.

Key words: land use type, agroforestry system, litter component, interception capacity, hydrological process.